//==========================================================================
// Copyright (c) 2000-2008,  Elastos, Inc.  All Rights Reserved.
//==========================================================================
/*****************************************************************************
* lcp.c - Network Link Control Protocol program file.
*
* Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
* portions Copyright (c) 1997 by Global Election Systems Inc.
*
* The authors hereby grant permission to use, copy, modify, distribute,
* and license this software and its documentation for any purpose, provided
* that existing copyright notices are retained in all copies and that this
* notice and the following disclaimer are included verbatim in any
* distributions. No written agreement, license, or royalty fee is required
* for any of the authorized uses.
*
* THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
******************************************************************************
* REVISION HISTORY
*
* 03-01-01 Marc Boucher <marc@mbsi.ca>
*   Ported to lwIP.
* 97-12-01 Guy Lancaster <lancasterg@acm.org>, Global Election Systems Inc.
* Original.
*****************************************************************************/

/*
 * lcp.c - PPP Link Control Protocol.
 *
 * Copyright (c) 1989 Carnegie Mellon University.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by Carnegie Mellon University.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#include <string.h>
#include <stdio.h>

#include "ppp.h"
#if PPP_SUPPORT > 0
#include "fsm.h"
#include "chap.h"
#include "magic.h"
#include "auth.h"
#include "lcp.h"
#include "pppdebug.h"
#include "_sprintf.h"

/*************************/
/*** LOCAL DEFINITIONS ***/
/*************************/
/*
 * Length of each type of configuration option (in octets)
 */
#define CILEN_VOID	2
#define CILEN_CHAR	3
#define CILEN_SHORT	4	/* CILEN_VOID + sizeof(short) */
#define CILEN_CHAP	5	/* CILEN_VOID + sizeof(short) + 1 */
#define CILEN_LONG	6	/* CILEN_VOID + sizeof(long) */
#define CILEN_LQR	8	/* CILEN_VOID + sizeof(short) + sizeof(long) */
#define CILEN_CBCP	3

/***********************************/
/*** LOCAL FUNCTION DECLARATIONS ***/
/***********************************/
/*
 * Callbacks for fsm code.  (CI = Configuration Information)
 */
static void lcp_resetci (fsm*);         /* Reset our CI */
static int  lcp_cilen (fsm*);          /* Return length of our CI */
static void lcp_addci (fsm*, u_char*, int*);       /* Add our CI to pkt */
static int  lcp_ackci (fsm*, u_char*, int);/* Peer ack'd our CI */
static int  lcp_nakci (fsm*, u_char*, int);/* Peer nak'd our CI */
static int  lcp_rejci (fsm*, u_char*, int);/* Peer rej'd our CI */
static int  lcp_reqci (fsm*, u_char*, int*, int);  /* Rcv peer CI */
static void lcp_up (fsm*);              /* We're UP */
static void lcp_down (fsm*);          /* We're DOWN */
static void lcp_starting (fsm*);        /* We need lower layer up */
static void lcp_finished (fsm*);         /* We need lower layer down */
static int  lcp_extcode (fsm*, int, u_char, u_char*, int);

static void lcp_rprotrej (fsm*, u_char*, int);

/*
 * routines to send LCP echos to peer
 */
static void lcp_echo_lowerup (int);
static void lcp_echo_lowerdown (int);
static void LcpEchoTimeout (void*);
static void lcp_received_echo_reply (fsm*, int, u_char*, int);
static void LcpSendEchoRequest (fsm*);
static void LcpLinkFailure (fsm*);
static void LcpEchoCheck (fsm*);

/*
 * Protocol entry points.
 * Some of these are called directly.
 */
static void lcp_input (int, u_char *, int);
static void lcp_protrej (int);

#define CODENAME(x) ((x) == CONFACK ? "ACK" : \
             (x) == CONFNAK ? "NAK" : "REJ")

/******************************/
/*** PUBLIC DATA STRUCTURES ***/
/******************************/
/* global vars */
LinkPhase lcp_phase[NUM_PPP];			/* Phase of link session (RFC 1661) */
lcp_options lcp_wantoptions[NUM_PPP];	/* Options that we want to request */
lcp_options lcp_gotoptions[NUM_PPP];	/* Options that peer ack'd */
lcp_options lcp_allowoptions[NUM_PPP];	/* Options we allow peer to request */
lcp_options lcp_hisoptions[NUM_PPP];	/* Options that we ack'd */
ext_accm xmit_accm[NUM_PPP];			/* extended transmit ACCM */

/*****************************/
/*** LOCAL DATA STRUCTURES ***/
/*****************************/
static fsm lcp_fsm[NUM_PPP];   /* LCP fsm structure (global)*/
static u_int  lcp_echo_interval = LCP_ECHOINTERVAL; /* Interval between LCP echo-requests */
static u_int  lcp_echo_fails = LCP_MAXECHOFAILS; /* Tolerance to unanswered echo-requests */
static u32_t lcp_echos_pending = 0; /* Number of outstanding echo msgs */
static u32_t lcp_echo_number   = 0; /* ID number of next echo frame */
static u32_t lcp_echo_timer_running = 0;  /* TRUE if a timer is running */

static u_char nak_buffer[PPP_MRU]; /* where we construct a nak packet */

static fsm_callbacks lcp_callbacks = {	/* LCP callback routines */
    lcp_resetci,		/* Reset our Configuration Information */
    lcp_cilen,			/* Length of our Configuration Information */
    lcp_addci,			/* Add our Configuration Information */
    lcp_ackci,			/* ACK our Configuration Information */
    lcp_nakci,			/* NAK our Configuration Information */
    lcp_rejci,			/* Reject our Configuration Information */
    lcp_reqci,			/* Request peer's Configuration Information */
    lcp_up,				/* Called when fsm reaches OPENED state */
    lcp_down,			/* Called when fsm leaves OPENED state */
    lcp_starting,		/* Called when we want the lower layer up */
    lcp_finished,		/* Called when we want the lower layer down */
    NULL,				/* Called when Protocol-Reject received */
    NULL,				/* Retransmission is necessary */
    lcp_extcode,		/* Called to handle LCP-specific codes */
    "LCP"				/* String name of protocol */
};

struct protent lcp_protent = {
    PPP_LCP,
    lcp_init,
    lcp_input,
    lcp_protrej,
    lcp_lowerup,
    lcp_lowerdown,
    lcp_open,
    lcp_close,
#if 0
    lcp_printpkt,
    NULL,
#endif
    1,
    "LCP",
#if 0
    NULL,
    NULL,
    NULL
#endif
};

int lcp_loopbackfail = DEFLOOPBACKFAIL;

/***********************************/
/*** PUBLIC FUNCTION DEFINITIONS ***/
/***********************************/
/*
 * lcp_init - Initialize LCP.
 */
void lcp_init(int unit)
{
    fsm *f = &lcp_fsm[unit];
    lcp_options *wo = &lcp_wantoptions[unit];
    lcp_options *ao = &lcp_allowoptions[unit];

    f->unit = unit;
    f->protocol = PPP_LCP;
    f->callbacks = &lcp_callbacks;

    fsm_init(f);

    wo->passive = 0;
    wo->silent = 0;
    wo->restart = 0;   /* Set to 1 in kernels or multi-line
                                 * implementations */
    wo->neg_mru = 1;
    wo->mru = PPP_DEFMRU;
    wo->neg_asyncmap = 1;
    wo->asyncmap = 0x00000000l; /* Assume don't need to escape any ctl chars. */
    wo->neg_chap = 0;   /* Set to 1 on server */
    wo->neg_upap = 0;   /* Set to 1 on server */
    wo->chap_mdtype = CHAP_DIGEST_MD5;
    wo->neg_magicnumber = 1;
    wo->neg_pcompression = 1;
    wo->neg_accompression = 1;
    wo->neg_lqr = 0;   /* no LQR implementation yet */
    wo->neg_cbcp = 0;

    ao->neg_mru = 1;
    ao->mru = PPP_MAXMRU;
    ao->neg_asyncmap = 1;
    ao->asyncmap = 0x00000000l; /* Assume don't need to escape any ctl chars. */
    ao->neg_chap = (CHAP_SUPPORT != 0);
    ao->chap_mdtype = CHAP_DIGEST_MD5;
    ao->neg_upap = (PAP_SUPPORT != 0);
    ao->neg_magicnumber = 1;
    ao->neg_pcompression = 1;
    ao->neg_accompression = 1;
    ao->neg_lqr = 0;   /* no LQR implementation yet */
    ao->neg_cbcp = (CBCP_SUPPORT != 0);

    /*
     * Set transmit escape for the flag and escape characters plus anything
     * set for the allowable options.
     */
    memset(xmit_accm[unit], 0, sizeof(xmit_accm[0]));
    xmit_accm[unit][15] = 0x60;
    xmit_accm[unit][0] = (u_char)(ao->asyncmap & 0xFF);
    xmit_accm[unit][1] = (u_char)((ao->asyncmap >> 8) & 0xFF);
    xmit_accm[unit][2] = (u_char)((ao->asyncmap >> 16) & 0xFF);
    xmit_accm[unit][3] = (u_char)((ao->asyncmap >> 24) & 0xFF);
    LCPDEBUG((LOG_INFO, "lcp_init: xmit_accm=%X %X %X %X\n",
                xmit_accm[unit][0],
                xmit_accm[unit][1],
                xmit_accm[unit][2],
                xmit_accm[unit][3]));

    lcp_phase[unit] = PHASE_INITIALIZE;
}

/*
 * lcp_open - LCP is allowed to come up.
 */
void lcp_open(int unit)
{
    fsm *f = &lcp_fsm[unit];
    lcp_options *wo = &lcp_wantoptions[unit];

    f->flags = 0;
    if (wo->passive)
        f->flags |= OPT_PASSIVE;
    if (wo->silent)
        f->flags |= OPT_SILENT;
    fsm_open(f);

    lcp_phase[unit] = PHASE_ESTABLISH;
}

/*
 * lcp_close - Take LCP down.
 */
void lcp_close(int unit, char *reason)
{
    fsm *f = &lcp_fsm[unit];

    if (lcp_phase[unit] != PHASE_DEAD)
        lcp_phase[unit] = PHASE_TERMINATE;
    if (f->state == STOPPED && f->flags & (OPT_PASSIVE|OPT_SILENT)) {
        /*
         * This action is not strictly according to the FSM in RFC1548,
         * but it does mean that the program terminates if you do an
         * lcp_close() in passive/silent mode when a connection hasn't
         * been established.
         */
        f->state = CLOSED;
        lcp_finished(f);
    }
    else
        fsm_close(&lcp_fsm[unit], reason);
}

/*
 * lcp_lowerup - The lower layer is up.
 */
void lcp_lowerup(int unit)
{
    lcp_options *wo = &lcp_wantoptions[unit];

    /*
    * Don't use A/C or protocol compression on transmission,
    * but accept A/C and protocol compressed packets
    * if we are going to ask for A/C and protocol compression.
    */
    ppp_set_xaccm(unit, &xmit_accm[unit]);
    ppp_send_config(unit, PPP_MRU, 0xffffffffl, 0, 0);
    ppp_recv_config(unit, PPP_MRU, 0x00000000l,
                    wo->neg_pcompression, wo->neg_accompression);
    peer_mru[unit] = PPP_MRU;
    lcp_allowoptions[unit].asyncmap
        = (u_long)xmit_accm[unit][0]
            | ((u_long)xmit_accm[unit][1] << 8)
            | ((u_long)xmit_accm[unit][2] << 16)
            | ((u_long)xmit_accm[unit][3] << 24);
    LCPDEBUG((LOG_INFO, "lcp_lowerup: asyncmap=%X %X %X %X\n",
                xmit_accm[unit][3],
                xmit_accm[unit][2],
                xmit_accm[unit][1],
                xmit_accm[unit][0]));

    fsm_lowerup(&lcp_fsm[unit]);
}

/*
 * lcp_lowerdown - The lower layer is down.
 */
void lcp_lowerdown(int unit)
{
    fsm_lowerdown(&lcp_fsm[unit]);
}

/*
 * lcp_sprotrej - Send a Protocol-Reject for some protocol.
 */
void lcp_sprotrej(int unit, u_char *p, int len)
{
    /*
    * Send back the protocol and the information field of the
    * rejected packet.  We only get here if LCP is in the OPENED state.
    */

    fsm_sdata(&lcp_fsm[unit], PROTREJ, ++lcp_fsm[unit].id,
                p, len);
}

/**********************************/
/*** LOCAL FUNCTION DEFINITIONS ***/
/**********************************/
/*
 * lcp_input - Input LCP packet.
 */
static void lcp_input(int unit, u_char *p, int len)
{
    fsm *f = &lcp_fsm[unit];

    fsm_input(f, p, len);
}

/*
 * lcp_extcode - Handle a LCP-specific code.
 */
static int lcp_extcode(fsm *f, int code, u_char id, u_char *inp, int len)
{
    u_char *magp;

    switch (code) {
        case PROTREJ:
            lcp_rprotrej(f, inp, len);
            break;

        case ECHOREQ:
            if (f->state != OPENED)
                break;
        LCPDEBUG((LOG_INFO, "lcp: Echo-Request, Rcvd id %d\n", id));
        magp = inp;
        PUTLONG(lcp_gotoptions[f->unit].magicnumber, magp);
        fsm_sdata(f, ECHOREP, id, inp, len);
        break;

        case ECHOREP:
            lcp_received_echo_reply(f, id, inp, len);
            break;

        case DISCREQ:
            break;

        default:
            return 0;
    }
    return 1;
}

/*
 * lcp_rprotrej - Receive an Protocol-Reject.
 *
 * Figure out which protocol is rejected and inform it.
 */
static void lcp_rprotrej(fsm *f, u_char *inp, int len)
{
    int i;
    struct protent *protp;
    u_short prot;

    if (len < sizeof (u_short)) {
        LCPDEBUG((LOG_INFO,
                "lcp_rprotrej: Rcvd short Protocol-Reject packet!\n"));
        return;
    }

    GETSHORT(prot, inp);

    LCPDEBUG((LOG_INFO,
            "lcp_rprotrej: Rcvd Protocol-Reject packet for %x!\n",
            prot));

    /*
    * Protocol-Reject packets received in any state other than the LCP
    * OPENED state SHOULD be silently discarded.
    */
    if (f->state != OPENED) {
        LCPDEBUG((LOG_INFO, "Protocol-Reject discarded: LCP in state %d\n",
                f->state));
        return;
    }

    /*
    * Upcall the proper Protocol-Reject routine.
    */
    for (i = 0; (protp = ppp_protocols[i]) != NULL;++i)
        if (protp->protocol == prot && protp->enabled_flag) {
            (*protp->protrej)(f->unit);
            return;
        }

    LCPDEBUG((LOG_WARNING, "Protocol-Reject for unsupported protocol 0x%x\n",
            prot));
}

/*
 * lcp_protrej - A Protocol-Reject was received.
 */
static void lcp_protrej(int unit)
{
    (void)unit;
    /*
    * Can't reject LCP!
    */
    LCPDEBUG((LOG_WARNING,
            "lcp_protrej: Received Protocol-Reject for LCP!\n"));
    fsm_protreject(&lcp_fsm[unit]);
}

/*
 * lcp_resetci - Reset our CI.
 */
static void lcp_resetci(fsm *f)
{
    lcp_wantoptions[f->unit].magicnumber = magic();
    lcp_wantoptions[f->unit].numloops = 0;
    lcp_gotoptions[f->unit] = lcp_wantoptions[f->unit];
    peer_mru[f->unit] = PPP_MRU;
    auth_reset(f->unit);
}

/*
 * lcp_cilen - Return length of our CI.
 */
static int lcp_cilen(fsm *f)
{
    lcp_options *go = &lcp_gotoptions[f->unit];

#define LENCIVOID(neg) ((neg) ? CILEN_VOID : 0)
#define LENCICHAP(neg) ((neg) ? CILEN_CHAP : 0)
#define LENCISHORT(neg) ((neg) ? CILEN_SHORT : 0)
#define LENCILONG(neg) ((neg) ? CILEN_LONG : 0)
#define LENCILQR(neg) ((neg) ? CILEN_LQR: 0)
#define LENCICBCP(neg) ((neg) ? CILEN_CBCP: 0)
    /*
    * NB: we only ask for one of CHAP and UPAP, even if we will
    * accept either.
    */
    return (LENCISHORT(go->neg_mru && go->mru != PPP_DEFMRU) +
        LENCILONG(go->neg_asyncmap && go->asyncmap != 0xFFFFFFFFl) +
        LENCICHAP(go->neg_chap) +
        LENCISHORT(!go->neg_chap && go->neg_upap) +
        LENCILQR(go->neg_lqr) +
        LENCICBCP(go->neg_cbcp) +
        LENCILONG(go->neg_magicnumber) +
        LENCIVOID(go->neg_pcompression) +
        LENCIVOID(go->neg_accompression));
}

/*
 * lcp_addci - Add our desired CIs to a packet.
 */
static void lcp_addci(fsm *f, u_char *ucp, int *lenp)
{
    lcp_options *go = &lcp_gotoptions[f->unit];
    u_char *start_ucp = ucp;

#define ADDCIVOID(opt, neg) \
    if (neg) { \
        LCPDEBUG((LOG_INFO, "lcp_addci: opt=%d\n", opt)); \
        PUTCHAR(opt, ucp); \
        PUTCHAR(CILEN_VOID, ucp); \
    }
#define ADDCISHORT(opt, neg, val) \
	if (neg) { \
	    LCPDEBUG((LOG_INFO, "lcp_addci: Int32 opt=%d %X\n", opt, val)); \
		PUTCHAR(opt, ucp); \
		PUTCHAR(CILEN_SHORT, ucp); \
		PUTSHORT(val, ucp); \
	}
#define ADDCICHAP(opt, neg, val, digest) \
    if (neg) { \
        LCPDEBUG((LOG_INFO, "lcp_addci: CHAP opt=%d %X\n", opt, val)); \
        PUTCHAR(opt, ucp); \
        PUTCHAR(CILEN_CHAP, ucp); \
        PUTSHORT(val, ucp); \
        PUTCHAR(digest, ucp); \
    }
#define ADDCILONG(opt, neg, val) \
    if (neg) { \
        LCPDEBUG((LOG_INFO, "lcp_addci: L opt=%d %lX\n", opt, val)); \
        PUTCHAR(opt, ucp); \
        PUTCHAR(CILEN_LONG, ucp); \
        PUTLONG(val, ucp); \
    }
#define ADDCILQR(opt, neg, val) \
    if (neg) { \
        LCPDEBUG((LOG_INFO, "lcp_addci: LQR opt=%d %lX\n", opt, val)); \
        PUTCHAR(opt, ucp); \
        PUTCHAR(CILEN_LQR, ucp); \
        PUTSHORT(PPP_LQR, ucp); \
        PUTLONG(val, ucp); \
    }
#define ADDCICHAR(opt, neg, val) \
    if (neg) { \
        LCPDEBUG((LOG_INFO, "lcp_addci: CHAR opt=%d %X '%z'\n", opt, val, val)); \
        PUTCHAR(opt, ucp); \
        PUTCHAR(CILEN_CHAR, ucp); \
        PUTCHAR(val, ucp); \
    }

    ADDCISHORT(CI_MRU, go->neg_mru && go->mru != PPP_DEFMRU, go->mru);
    ADDCILONG(CI_ASYNCMAP, go->neg_asyncmap && go->asyncmap != 0xFFFFFFFFl,
            go->asyncmap);
    ADDCICHAP(CI_AUTHTYPE, go->neg_chap, PPP_CHAP, go->chap_mdtype);
    ADDCISHORT(CI_AUTHTYPE, !go->neg_chap && go->neg_upap, PPP_PAP);
    ADDCILQR(CI_QUALITY, go->neg_lqr, go->lqr_period);
    ADDCICHAR(CI_CALLBACK, go->neg_cbcp, CBCP_OPT);
    ADDCILONG(CI_MAGICNUMBER, go->neg_magicnumber, go->magicnumber);
    ADDCIVOID(CI_PCOMPRESSION, go->neg_pcompression);
    ADDCIVOID(CI_ACCOMPRESSION, go->neg_accompression);

    if (ucp - start_ucp != *lenp) {
        /* this should never happen, because peer_mtu should be 1500 */
        LCPDEBUG((LOG_ERR, "Bug in lcp_addci: wrong length\n"));
    }
}

/*
 * lcp_ackci - Ack our CIs.
 * This should not modify any state if the Ack is bad.
 *
 * Returns:
 * 0 - Ack was bad.
 * 1 - Ack was good.
 */
static int lcp_ackci(fsm *f, u_char *p, int len)
{
    lcp_options *go = &lcp_gotoptions[f->unit];
    u_char cilen, citype, cichar;
    u_short cishort;
    u32_t cilong;

    /*
    * CIs must be in exactly the same order that we sent.
    * Check packet length and CI length at each step.
    * If we find any deviations, then this packet is bad.
    */
#define ACKCIVOID(opt, neg) \
    if (neg) { \
        if ((len -= CILEN_VOID) < 0) \
            goto bad; \
        GETCHAR(citype, p); \
        GETCHAR(cilen, p); \
        if (cilen != CILEN_VOID || \
                citype != opt) \
            goto bad; \
    }
#define ACKCISHORT(opt, neg, val) \
    if (neg) { \
        if ((len -= CILEN_SHORT) < 0) \
            goto bad; \
        GETCHAR(citype, p); \
        GETCHAR(cilen, p); \
        if (cilen != CILEN_SHORT || \
                citype != opt) \
            goto bad; \
        GETSHORT(cishort, p); \
        if (cishort != val) \
            goto bad; \
    }
#define ACKCICHAR(opt, neg, val) \
    if (neg) { \
        if ((len -= CILEN_CHAR) < 0) \
            goto bad; \
        GETCHAR(citype, p); \
        GETCHAR(cilen, p); \
        if (cilen != CILEN_CHAR || \
                citype != opt) \
            goto bad; \
        GETCHAR(cichar, p); \
        if (cichar != val) \
            goto bad; \
    }
#define ACKCICHAP(opt, neg, val, digest) \
    if (neg) { \
        if ((len -= CILEN_CHAP) < 0) \
            goto bad; \
        GETCHAR(citype, p); \
        GETCHAR(cilen, p); \
        if (cilen != CILEN_CHAP || \
                citype != opt) \
            goto bad; \
        GETSHORT(cishort, p); \
        if (cishort != val) \
            goto bad; \
        GETCHAR(cichar, p); \
        if (cichar != digest) \
            goto bad; \
    }
#define ACKCILONG(opt, neg, val) \
    if (neg) { \
        if ((len -= CILEN_LONG) < 0) \
            goto bad; \
        GETCHAR(citype, p); \
        GETCHAR(cilen, p); \
        if (cilen != CILEN_LONG || \
                citype != opt) \
            goto bad; \
        GETLONG(cilong, p); \
        if (cilong != val) \
            goto bad; \
    }
#define ACKCILQR(opt, neg, val) \
    if (neg) { \
        if ((len -= CILEN_LQR) < 0) \
            goto bad; \
        GETCHAR(citype, p); \
        GETCHAR(cilen, p); \
        if (cilen != CILEN_LQR || \
                citype != opt) \
            goto bad; \
        GETSHORT(cishort, p); \
        if (cishort != PPP_LQR) \
            goto bad; \
        GETLONG(cilong, p); \
        if (cilong != val) \
            goto bad; \
    }

    ACKCISHORT(CI_MRU, go->neg_mru && go->mru != PPP_DEFMRU, go->mru);
    ACKCILONG(CI_ASYNCMAP, go->neg_asyncmap && go->asyncmap != 0xFFFFFFFFl,
            go->asyncmap);
    ACKCICHAP(CI_AUTHTYPE, go->neg_chap, PPP_CHAP, go->chap_mdtype);
    ACKCISHORT(CI_AUTHTYPE, !go->neg_chap && go->neg_upap, PPP_PAP);
    ACKCILQR(CI_QUALITY, go->neg_lqr, go->lqr_period);
    ACKCICHAR(CI_CALLBACK, go->neg_cbcp, CBCP_OPT);
    ACKCILONG(CI_MAGICNUMBER, go->neg_magicnumber, go->magicnumber);
    ACKCIVOID(CI_PCOMPRESSION, go->neg_pcompression);
    ACKCIVOID(CI_ACCOMPRESSION, go->neg_accompression);

    /*
     * If there are any remaining CIs, then this packet is bad.
     */
    if (len != 0)
        goto bad;
    LCPDEBUG((LOG_INFO, "lcp_acki: Ack\n"));
    return (1);
bad:
    LCPDEBUG((LOG_WARNING, "lcp_acki: received bad Ack!\n"));
    return (0);
}

/*
 * lcp_nakci - Peer has sent a NAK for some of our CIs.
 * This should not modify any state if the Nak is bad
 * or if LCP is in the OPENED state.
 *
 * Returns:
 * 0 - Nak was bad.
 * 1 - Nak was good.
 */
static int lcp_nakci(fsm *f, u_char *p, int len)
{
    lcp_options *go = &lcp_gotoptions[f->unit];
    lcp_options *wo = &lcp_wantoptions[f->unit];
    u_char citype, cichar, *next;
    u_short cishort;
    u32_t cilong;
    lcp_options no;  /* options we've seen Naks for */
    lcp_options try;  /* options to request next time */
    int looped_back = 0;
    int cilen;

    BZERO(&no, sizeof(no));
    try = *go;

    /*
    * Any Nak'd CIs must be in exactly the same order that we sent.
    * Check packet length and CI length at each step.
    * If we find any deviations, then this packet is bad.
    */
#define NAKCIVOID(opt, neg, code) \
    if (go->neg && \
            len >= CILEN_VOID && \
            p[1] == CILEN_VOID && \
            p[0] == opt) { \
        len -= CILEN_VOID; \
        INCPTR(CILEN_VOID, p); \
        no.neg = 1; \
        code \
    }
#define NAKCICHAP(opt, neg, code) \
    if (go->neg && \
            len >= CILEN_CHAP && \
            p[1] == CILEN_CHAP && \
            p[0] == opt) { \
        len -= CILEN_CHAP; \
        INCPTR(2, p); \
        GETSHORT(cishort, p); \
        GETCHAR(cichar, p); \
        no.neg = 1; \
        code \
    }
#define NAKCICHAR(opt, neg, code) \
    if (go->neg && \
            len >= CILEN_CHAR && \
            p[1] == CILEN_CHAR && \
            p[0] == opt) { \
        len -= CILEN_CHAR; \
        INCPTR(2, p); \
        GETCHAR(cichar, p); \
        no.neg = 1; \
        code \
    }
#define NAKCISHORT(opt, neg, code) \
    if (go->neg && \
            len >= CILEN_SHORT && \
            p[1] == CILEN_SHORT && \
            p[0] == opt) { \
        len -= CILEN_SHORT; \
        INCPTR(2, p); \
        GETSHORT(cishort, p); \
        no.neg = 1; \
        code \
    }
#define NAKCILONG(opt, neg, code) \
    if (go->neg && \
            len >= CILEN_LONG && \
            p[1] == CILEN_LONG && \
            p[0] == opt) { \
        len -= CILEN_LONG; \
        INCPTR(2, p); \
        GETLONG(cilong, p); \
        no.neg = 1; \
        code \
    }
#define NAKCILQR(opt, neg, code) \
    if (go->neg && \
            len >= CILEN_LQR && \
            p[1] == CILEN_LQR && \
            p[0] == opt) { \
        len -= CILEN_LQR; \
        INCPTR(2, p); \
        GETSHORT(cishort, p); \
        GETLONG(cilong, p); \
        no.neg = 1; \
        code \
    }

    /*
    * We don't care if they want to send us smaller packets than
    * we want.  Therefore, accept any MRU less than what we asked for,
    * but then ignore the new value when setting the MRU in the kernel.
    * If they send us a bigger MRU than what we asked, accept it, up to
    * the limit of the default MRU we'd get if we didn't negotiate.
    */
    if (go->neg_mru && go->mru != PPP_DEFMRU) {
        NAKCISHORT(CI_MRU, neg_mru,
            if (cishort <= wo->mru || cishort < PPP_DEFMRU)
                try.mru = cishort;
        );
    }

    /*
    * Add any characters they want to our (receive-side) asyncmap.
    */
    if (go->neg_asyncmap && go->asyncmap != 0xFFFFFFFFl) {
        NAKCILONG(CI_ASYNCMAP, neg_asyncmap,
            try.asyncmap = go->asyncmap | cilong;
        );
    }

    /*
    * If they've nak'd our authentication-protocol, check whether
    * they are proposing a different protocol, or a different
    * hash algorithm for CHAP.
    */
    if ((go->neg_chap || go->neg_upap)
        && len >= CILEN_SHORT
        && p[0] == CI_AUTHTYPE && p[1] >= CILEN_SHORT && p[1] <= len) {
        cilen = p[1];
        len -= cilen;
        no.neg_chap = go->neg_chap;
        no.neg_upap = go->neg_upap;
        INCPTR(2, p);
        GETSHORT(cishort, p);
        if (cishort == PPP_PAP && cilen == CILEN_SHORT) {
            /*
         * If we were asking for CHAP, they obviously don't want to do it.
         * If we weren't asking for CHAP, then we were asking for PAP,
         * in which case this Nak is bad.
         */
            if (!go->neg_chap)
                goto bad;
            try.neg_chap = 0;
        }
        else if (cishort == PPP_CHAP && cilen == CILEN_CHAP) {
            GETCHAR(cichar, p);
            if (go->neg_chap) {
                /*
             * We were asking for CHAP/MD5; they must want a different
             * algorithm.  If they can't do MD5, we'll have to stop
             * asking for CHAP.
             */
                if (cichar != go->chap_mdtype)
                    try.neg_chap = 0;
            }
            else {
                /*
             * Stop asking for PAP if we were asking for it.
             */
                try.neg_upap = 0;
            }
        }
        else {
            /*
         * We don't recognize what they're suggesting.
         * Stop asking for what we were asking for.
         */
            if (go->neg_chap)
                try.neg_chap = 0;
            else
                try.neg_upap = 0;
            p += cilen - CILEN_SHORT;
        }
    }

    /*
    * If they can't cope with our link quality protocol, we'll have
    * to stop asking for LQR.  We haven't got any other protocol.
    * If they Nak the reporting period, take their value XXX ?
    */
    NAKCILQR(CI_QUALITY, neg_lqr,
        if (cishort != PPP_LQR)
            try.neg_lqr = 0;
    else
            try.lqr_period = cilong;
    );

    /*
    * Only implementing CBCP...not the rest of the callback options
    */
    NAKCICHAR(CI_CALLBACK, neg_cbcp,
        try.neg_cbcp = 0;
    );

    /*
    * Check for a looped-back line.
    */
    NAKCILONG(CI_MAGICNUMBER, neg_magicnumber,
        try.magicnumber = magic();
    looped_back = 1;
    );

    /*
    * Peer shouldn't send Nak for protocol compression or
    * address/control compression requests; they should send
    * a Reject instead.  If they send a Nak, treat it as a Reject.
    */
    NAKCIVOID(CI_PCOMPRESSION, neg_pcompression,
        try.neg_pcompression = 0;
    );
    NAKCIVOID(CI_ACCOMPRESSION, neg_accompression,
        try.neg_accompression = 0;
    );

    /*
    * There may be remaining CIs, if the peer is requesting negotiation
    * on an option that we didn't include in our request packet.
    * If we see an option that we requested, or one we've already seen
    * in this packet, then this packet is bad.
    * If we wanted to respond by starting to negotiate on the requested
    * option(s), we could, but we don't, because except for the
    * authentication type and quality protocol, if we are not negotiating
    * an option, it is because we were told not to.
    * For the authentication type, the Nak from the peer means
    * `let me authenticate myself with you' which is a bit pointless.
    * For the quality protocol, the Nak means `ask me to send you quality
    * reports', but if we didn't ask for them, we don't want them.
    * An option we don't recognize represents the peer asking to
    * negotiate some option we don't support, so ignore it.
    */
    while (len > CILEN_VOID) {
        GETCHAR(citype, p);
        GETCHAR(cilen, p);
        if (cilen < CILEN_VOID || (len -= cilen) < 0)
            goto bad;
        next = p + cilen - 2;

        switch (citype) {
            case CI_MRU:
                if ((go->neg_mru && go->mru != PPP_DEFMRU)
                    || no.neg_mru || cilen != CILEN_SHORT)
                    goto bad;
                GETSHORT(cishort, p);
                if (cishort < PPP_DEFMRU)
                    try.mru = cishort;
                break;
            case CI_ASYNCMAP:
                if ((go->neg_asyncmap && go->asyncmap != 0xFFFFFFFFl)
                    || no.neg_asyncmap || cilen != CILEN_LONG)
                    goto bad;
                break;
            case CI_AUTHTYPE:
                if (go->neg_chap || no.neg_chap || go->neg_upap || no.neg_upap)
                    goto bad;
                break;
            case CI_MAGICNUMBER:
                if (go->neg_magicnumber || no.neg_magicnumber ||
                    cilen != CILEN_LONG)
                    goto bad;
                break;
            case CI_PCOMPRESSION:
                if (go->neg_pcompression || no.neg_pcompression
                    || cilen != CILEN_VOID)
                    goto bad;
                break;
            case CI_ACCOMPRESSION:
                if (go->neg_accompression || no.neg_accompression
                    || cilen != CILEN_VOID)
                    goto bad;
                break;
            case CI_QUALITY:
                if (go->neg_lqr || no.neg_lqr || cilen != CILEN_LQR)
                    goto bad;
                break;
        }
        p = next;
    }

    /* If there is still anything left, this packet is bad. */
    if (len != 0)
        goto bad;

    /*
    * OK, the Nak is good.  Now we can update state.
    */
    if (f->state != OPENED) {
        if (looped_back) {
            if (++try.numloops >= lcp_loopbackfail) {
                LCPDEBUG((LOG_NOTICE, "Serial line is looped back.\n"));
                lcp_close(f->unit, "Loopback detected");
            }
        }
        else
            try.numloops = 0;
        *go = try;
    }

    return 1;

bad:
    LCPDEBUG((LOG_WARNING, "lcp_nakci: received bad Nak!\n"));
    return 0;
}

/*
 * lcp_rejci - Peer has Rejected some of our CIs.
 * This should not modify any state if the Reject is bad
 * or if LCP is in the OPENED state.
 *
 * Returns:
 * 0 - Reject was bad.
 * 1 - Reject was good.
 */
static int lcp_rejci(fsm *f, u_char *p, int len)
{
    lcp_options *go = &lcp_gotoptions[f->unit];
    u_char cichar;
    u_short cishort;
    u32_t cilong;
    lcp_options try;  /* options to request next time */

    try = *go;

    /*
    * Any Rejected CIs must be in exactly the same order that we sent.
    * Check packet length and CI length at each step.
    * If we find any deviations, then this packet is bad.
    */
#define REJCIVOID(opt, neg) \
    if (go->neg && \
            len >= CILEN_VOID && \
            p[1] == CILEN_VOID && \
            p[0] == opt) { \
        len -= CILEN_VOID; \
        INCPTR(CILEN_VOID, p); \
        try.neg = 0; \
        LCPDEBUG((LOG_INFO, "lcp_rejci: void opt %d rejected\n", opt)); \
    }
#define REJCISHORT(opt, neg, val) \
    if (go->neg && \
            len >= CILEN_SHORT && \
            p[1] == CILEN_SHORT && \
            p[0] == opt) { \
        len -= CILEN_SHORT; \
        INCPTR(2, p); \
        GETSHORT(cishort, p); \
        /* Check rejected value. */ \
        if (cishort != val) \
            goto bad; \
        try.neg = 0; \
        LCPDEBUG((LOG_INFO,"lcp_rejci: short opt %d rejected\n", opt)); \
    }
#define REJCICHAP(opt, neg, val, digest) \
    if (go->neg && \
            len >= CILEN_CHAP && \
            p[1] == CILEN_CHAP && \
            p[0] == opt) { \
        len -= CILEN_CHAP; \
        INCPTR(2, p); \
        GETSHORT(cishort, p); \
        GETCHAR(cichar, p); \
        /* Check rejected value. */ \
        if (cishort != val || cichar != digest) \
            goto bad; \
        try.neg = 0; \
        try.neg_upap = 0; \
        LCPDEBUG((LOG_INFO,"lcp_rejci: chap opt %d rejected\n", opt)); \
    }
#define REJCILONG(opt, neg, val) \
    if (go->neg && \
            len >= CILEN_LONG && \
            p[1] == CILEN_LONG && \
            p[0] == opt) { \
        len -= CILEN_LONG; \
        INCPTR(2, p); \
        GETLONG(cilong, p); \
        /* Check rejected value. */ \
        if (cilong != val) \
            goto bad; \
        try.neg = 0; \
        LCPDEBUG((LOG_INFO,"lcp_rejci: long opt %d rejected\n", opt)); \
    }
#define REJCILQR(opt, neg, val) \
    if (go->neg && \
            len >= CILEN_LQR && \
            p[1] == CILEN_LQR && \
            p[0] == opt) { \
        len -= CILEN_LQR; \
        INCPTR(2, p); \
        GETSHORT(cishort, p); \
        GETLONG(cilong, p); \
        /* Check rejected value. */ \
        if (cishort != PPP_LQR || cilong != val) \
            goto bad; \
        try.neg = 0; \
        LCPDEBUG((LOG_INFO,"lcp_rejci: LQR opt %d rejected\n", opt)); \
    }
#define REJCICBCP(opt, neg, val) \
    if (go->neg && \
            len >= CILEN_CBCP && \
            p[1] == CILEN_CBCP && \
            p[0] == opt) { \
        len -= CILEN_CBCP; \
        INCPTR(2, p); \
        GETCHAR(cichar, p); \
        /* Check rejected value. */ \
        if (cichar != val) \
            goto bad; \
        try.neg = 0; \
        LCPDEBUG((LOG_INFO,"lcp_rejci: Callback opt %d rejected\n", opt)); \
    }

    REJCISHORT(CI_MRU, neg_mru, go->mru);
    REJCILONG(CI_ASYNCMAP, neg_asyncmap, go->asyncmap);
    REJCICHAP(CI_AUTHTYPE, neg_chap, PPP_CHAP, go->chap_mdtype);
    if (!go->neg_chap) {
        REJCISHORT(CI_AUTHTYPE, neg_upap, PPP_PAP);
    }
    REJCILQR(CI_QUALITY, neg_lqr, go->lqr_period);
    REJCICBCP(CI_CALLBACK, neg_cbcp, CBCP_OPT);
    REJCILONG(CI_MAGICNUMBER, neg_magicnumber, go->magicnumber);
    REJCIVOID(CI_PCOMPRESSION, neg_pcompression);
    REJCIVOID(CI_ACCOMPRESSION, neg_accompression);

    /*
    * If there are any remaining CIs, then this packet is bad.
    */
    if (len != 0)
        goto bad;
    /*
    * Now we can update state.
    */
    if (f->state != OPENED)
        *go = try;
    return 1;

bad:
    LCPDEBUG((LOG_WARNING, "lcp_rejci: received bad Reject!\n"));
    return 0;
}

/*
 * lcp_reqci - Check the peer's requested CIs and send appropriate response.
 *
 * Returns: CONFACK, CONFNAK or CONFREJ and input packet modified
 * appropriately.  If reject_if_disagree is non-zero, doesn't return
 * CONFNAK; returns CONFREJ if it can't return CONFACK.
 */
static int lcp_reqci(fsm *f,
    u_char *inp, /* Requested CIs */
    int *lenp, /* Length of requested CIs */
    int reject_if_disagree)
{
    lcp_options *go = &lcp_gotoptions[f->unit];
    lcp_options *ho = &lcp_hisoptions[f->unit];
    lcp_options *ao = &lcp_allowoptions[f->unit];
    u_char *cip, *next;   /* Pointer to current and next CIs */
    int cilen, citype, cichar; /* Parsed len, type, char value */
    u_short cishort;   /* Parsed short value */
    u32_t cilong;   /* Parse long value */
    int rc = CONFACK;   /* Final packet return code */
    int orc;     /* Individual option return code */
    u_char *p;     /* Pointer to next char to parse */
    u_char *rejp;    /* Pointer to next char in reject frame */
    u_char *nakp;    /* Pointer to next char in Nak frame */
    int l = *lenp;    /* Length left */
#if TRACELCP > 0
    char traceBuf[80];
    int traceNdx = 0;
#endif

    /*
     * Reset all his options.
     */
    BZERO(ho, sizeof(*ho));

    /*
     * Process all his options.
     */
    next = inp;
    nakp = nak_buffer;
    rejp = inp;
    while (l) {
        orc = CONFACK;   /* Assume success */
        cip = p = next;   /* Remember begining of CI */
        if (l < 2 || /* Not enough data for CI header or */
            p[1] < 2 || /*  CI length too small or */
            p[1] > l) {   /*  CI length too big? */
            LCPDEBUG((LOG_WARNING, "lcp_reqci: bad CI length!\n"));
            orc = CONFREJ;  /* Reject bad CI */
            cilen = l;   /* Reject till end of packet */
            l = 0;   /* Don't loop again */
            citype = 0;
            goto endswitch;
        }
        GETCHAR(citype, p);  /* Parse CI type */
        GETCHAR(cilen, p);  /* Parse CI length */
        l -= cilen;   /* Adjust remaining length */
        next += cilen;   /* Step to next CI */

        switch (citype) {  /* Check CI type */
            case CI_MRU:
                if (!ao->neg_mru) {  /* Allow option? */
                    LCPDEBUG((LOG_INFO, "lcp_reqci: Reject MRU - not allowed\n"));
                    orc = CONFREJ;  /* Reject CI */
                    break;
                }
                else if (cilen != CILEN_SHORT) { /* Check CI length */
                    LCPDEBUG((LOG_INFO, "lcp_reqci: Reject MRU - bad length\n"));
                    orc = CONFREJ;  /* Reject CI */
                    break;
                }
                GETSHORT(cishort, p); /* Parse MRU */

                /*
             * He must be able to receive at least our minimum.
             * No need to check a maximum.  If he sends a large number,
             * we'll just ignore it.
             */
                if (cishort < PPP_MINMRU) {
                    LCPDEBUG((LOG_INFO, "lcp_reqci: Nak - MRU too small\n"));
                    orc = CONFNAK;  /* Nak CI */
                    PUTCHAR(CI_MRU, nakp);
                    PUTCHAR(CILEN_SHORT, nakp);
                    PUTSHORT(PPP_MINMRU, nakp); /* Give him a hint */
                    break;
                }
                ho->neg_mru = 1;  /* Remember he sent MRU */
                ho->mru = cishort;  /* And remember value */
#if TRACELCP > 0
                sprintf(&traceBuf[traceNdx], " MRU %d", cishort);
                traceNdx = strlen(traceBuf);
#endif
                break;

            case CI_ASYNCMAP:
                if (!ao->neg_asyncmap) {
                    LCPDEBUG((LOG_INFO, "lcp_reqci: Reject ASYNCMAP not allowed\n"));
                    orc = CONFREJ;
                    break;
                }
                else if (cilen != CILEN_LONG) {
                    LCPDEBUG((LOG_INFO, "lcp_reqci: Reject ASYNCMAP bad length\n"));
                    orc = CONFREJ;
                    break;
                }
                GETLONG(cilong, p);

                /*
             * Asyncmap must have set at least the bits
             * which are set in lcp_allowoptions[unit].asyncmap.
             */
                if ((ao->asyncmap & ~cilong) != 0) {
                    LCPDEBUG((LOG_INFO, "lcp_reqci: Nak ASYNCMAP %lX missing %lX\n",
                            cilong, ao->asyncmap));
                    orc = CONFNAK;
                    PUTCHAR(CI_ASYNCMAP, nakp);
                    PUTCHAR(CILEN_LONG, nakp);
                    PUTLONG(ao->asyncmap | cilong, nakp);
                    break;
                }
                ho->neg_asyncmap = 1;
                ho->asyncmap = cilong;
#if TRACELCP > 0
                sprintf(&traceBuf[traceNdx], " ASYNCMAP=%lX", cilong);
                traceNdx = strlen(traceBuf);
#endif
                break;

            case CI_AUTHTYPE:
                if (cilen < CILEN_SHORT) {
                    LCPDEBUG((LOG_INFO, "lcp_reqci: Reject AUTHTYPE missing arg\n"));
                    orc = CONFREJ;
                    break;
                }
                else if (!(ao->neg_upap || ao->neg_chap)) {
                    /*
                 * Reject the option if we're not willing to authenticate.
                 */
                    LCPDEBUG((LOG_INFO, "lcp_reqci: Reject AUTHTYPE not allowed\n"));
                    orc = CONFREJ;
                    break;
                }
                GETSHORT(cishort, p);

                /*
             * Authtype must be UPAP or CHAP.
             *
             * Note: if both ao->neg_upap and ao->neg_chap are set,
             * and the peer sends a Configure-Request with two
             * authenticate-protocol requests, one for CHAP and one
             * for UPAP, then we will reject the second request.
             * Whether we end up doing CHAP or UPAP depends then on
             * the ordering of the CIs in the peer's Configure-Request.
             */

                if (cishort == PPP_PAP) {
                    if (ho->neg_chap) { /* we've already accepted CHAP */
                        LCPDEBUG((LOG_WARNING, "lcp_reqci: Reject AUTHTYPE PAP already accepted\n"));
                        orc = CONFREJ;
                        break;
                    }
                    else if (cilen != CILEN_SHORT) {
                        LCPDEBUG((LOG_WARNING, "lcp_reqci: Reject AUTHTYPE PAP bad len\n"));
                        orc = CONFREJ;
                        break;
                    }
                    if (!ao->neg_upap) { /* we don't want to do PAP */
                        LCPDEBUG((LOG_WARNING, "lcp_reqci: Nak AUTHTYPE PAP not allowed\n"));
                        orc = CONFNAK; /* NAK it and suggest CHAP */
                        PUTCHAR(CI_AUTHTYPE, nakp);
                        PUTCHAR(CILEN_CHAP, nakp);
                        PUTSHORT(PPP_CHAP, nakp);
                        PUTCHAR(ao->chap_mdtype, nakp);
                        break;
                    }
                    ho->neg_upap = 1;
#if TRACELCP > 0
                    sprintf(&traceBuf[traceNdx], " PAP (%X)", cishort);
                    traceNdx = strlen(traceBuf);
#endif
                    break;
                }
                if (cishort == PPP_CHAP) {
                    if (ho->neg_upap) { /* we've already accepted PAP */
                        LCPDEBUG((LOG_WARNING, "lcp_reqci: Reject AUTHTYPE CHAP accepted PAP\n"));
                        orc = CONFREJ;
                        break;
                    }
                    else if (cilen != CILEN_CHAP) {
                        LCPDEBUG((LOG_WARNING, "lcp_reqci: Reject AUTHTYPE CHAP bad len\n"));
                        orc = CONFREJ;
                        break;
                    }
                    if (!ao->neg_chap) { /* we don't want to do CHAP */
                        LCPDEBUG((LOG_WARNING, "lcp_reqci: Nak AUTHTYPE CHAP not allowed\n"));
                        orc = CONFNAK; /* NAK it and suggest PAP */
                        PUTCHAR(CI_AUTHTYPE, nakp);
                        PUTCHAR(CILEN_SHORT, nakp);
                        PUTSHORT(PPP_PAP, nakp);
                        break;
                    }
                    GETCHAR(cichar, p); /* get digest type*/
                    if (cichar != CHAP_DIGEST_MD5
                        #ifdef CHAPMS
                        && cichar != CHAP_MICROSOFT
                        #endif
                        ) {
                        LCPDEBUG((LOG_WARNING, "lcp_reqci: Nak AUTHTYPE CHAP digest=%d\n", cichar));
                        orc = CONFNAK;
                        PUTCHAR(CI_AUTHTYPE, nakp);
                        PUTCHAR(CILEN_CHAP, nakp);
                        PUTSHORT(PPP_CHAP, nakp);
                        PUTCHAR(ao->chap_mdtype, nakp);
                        break;
                    }
#if TRACELCP > 0
                    sprintf(&traceBuf[traceNdx], " CHAP %X,%d", cishort, cichar);
                    traceNdx = strlen(traceBuf);
#endif
                    ho->chap_mdtype = cichar; /* save md type */
                    ho->neg_chap = 1;
                    break;
                }

                /*
             * We don't recognize the protocol they're asking for.
             * Nak it with something we're willing to do.
             * (At this point we know ao->neg_upap || ao->neg_chap.)
             */
                orc = CONFNAK;
                PUTCHAR(CI_AUTHTYPE, nakp);
                if (ao->neg_chap) {
                    LCPDEBUG((LOG_WARNING, "lcp_reqci: Nak AUTHTYPE %d req CHAP\n", cishort));
                    PUTCHAR(CILEN_CHAP, nakp);
                    PUTSHORT(PPP_CHAP, nakp);
                    PUTCHAR(ao->chap_mdtype, nakp);
                }
                else {
                    LCPDEBUG((LOG_WARNING, "lcp_reqci: Nak AUTHTYPE %d req PAP\n", cishort));
                    PUTCHAR(CILEN_SHORT, nakp);
                    PUTSHORT(PPP_PAP, nakp);
                }
                break;

            case CI_QUALITY:
                GETSHORT(cishort, p);
                GETLONG(cilong, p);
#if TRACELCP > 0
                sprintf(&traceBuf[traceNdx], " QUALITY (%x %x)", cishort, (unsigned int) cilong);
                traceNdx = strlen(traceBuf);
#endif

                if (!ao->neg_lqr ||
                    cilen != CILEN_LQR) {
                    orc = CONFREJ;
                    break;
                }

                /*
             * Check the protocol and the reporting period.
             * XXX When should we Nak this, and what with?
             */
                if (cishort != PPP_LQR) {
                    orc = CONFNAK;
                    PUTCHAR(CI_QUALITY, nakp);
                    PUTCHAR(CILEN_LQR, nakp);
                    PUTSHORT(PPP_LQR, nakp);
                    PUTLONG(ao->lqr_period, nakp);
                    break;
                }
                break;

            case CI_MAGICNUMBER:
                if (!(ao->neg_magicnumber || go->neg_magicnumber) ||
                    cilen != CILEN_LONG) {
                    orc = CONFREJ;
                    break;
                }
                GETLONG(cilong, p);
#if TRACELCP > 0
                sprintf(&traceBuf[traceNdx], " MAGICNUMBER (%lX)", cilong);
                traceNdx = strlen(traceBuf);
#endif

                /*
             * He must have a different magic number.
             */
                if (go->neg_magicnumber &&
                    cilong == go->magicnumber) {
                    cilong = magic(); /* Don't put magic() inside macro! */
                    orc = CONFNAK;
                    PUTCHAR(CI_MAGICNUMBER, nakp);
                    PUTCHAR(CILEN_LONG, nakp);
                    PUTLONG(cilong, nakp);
                    break;
                }
                ho->neg_magicnumber = 1;
                ho->magicnumber = cilong;
                break;

            case CI_PCOMPRESSION:
#if TRACELCP > 0
                sprintf(&traceBuf[traceNdx], " PCOMPRESSION");
                traceNdx = strlen(traceBuf);
#endif
                if (!ao->neg_pcompression ||
                    cilen != CILEN_VOID) {
                    orc = CONFREJ;
                    break;
                }
                ho->neg_pcompression = 1;
                break;

            case CI_ACCOMPRESSION:
#if TRACELCP > 0
                sprintf(&traceBuf[traceNdx], " ACCOMPRESSION");
                traceNdx = strlen(traceBuf);
#endif
                if (!ao->neg_accompression ||
                    cilen != CILEN_VOID) {
                    orc = CONFREJ;
                    break;
                }
                ho->neg_accompression = 1;
                break;

            case CI_MRRU:
#if TRACELCP > 0
                sprintf(&traceBuf[traceNdx], " CI_MRRU");
                traceNdx = strlen(traceBuf);
#endif
                orc = CONFREJ;
                break;

            case CI_SSNHF:
#if TRACELCP > 0
                sprintf(&traceBuf[traceNdx], " CI_SSNHF");
                traceNdx = strlen(traceBuf);
#endif
                orc = CONFREJ;
                break;

            case CI_EPDISC:
#if TRACELCP > 0
                sprintf(&traceBuf[traceNdx], " CI_EPDISC");
                traceNdx = strlen(traceBuf);
#endif
                orc = CONFREJ;
                break;

            default:
#if TRACELCP
                sprintf(&traceBuf[traceNdx], " unknown %d", citype);
                traceNdx = strlen(traceBuf);
#endif
                orc = CONFREJ;
                break;
        }

    endswitch:
#if TRACELCP
        if (traceNdx >= 80 - 32) {
            LCPDEBUG((LOG_INFO, "lcp_reqci: rcvd%s\n", traceBuf));
            traceNdx = 0;
        }
#endif
        if (orc == CONFACK && /* Good CI */
            rc != CONFACK) /*  but prior CI wasnt? */
            continue;   /* Don't send this one */

        if (orc == CONFNAK) {  /* Nak this CI? */
            if (reject_if_disagree /* Getting fed up with sending NAKs? */
                && citype != CI_MAGICNUMBER) {
                orc = CONFREJ;  /* Get tough if so */
            }
            else {
                if (rc == CONFREJ) /* Rejecting prior CI? */
                    continue;  /* Don't send this one */
                rc = CONFNAK;
            }
        }
        if (orc == CONFREJ) {  /* Reject this CI */
            rc = CONFREJ;
            if (cip != rejp) /* Need to move rejected CI? */
                BCOPY(cip, rejp, cilen); /* Move it */
            INCPTR(cilen, rejp); /* Update output pointer */
        }
    }

    /*
     * If we wanted to send additional NAKs (for unsent CIs), the
     * code would go here.  The extra NAKs would go at *nakp.
     * At present there are no cases where we want to ask the
     * peer to negotiate an option.
     */

    switch (rc) {
        case CONFACK:
            *lenp = (int)(next - inp);
            break;
        case CONFNAK:
            /*
         * Copy the Nak'd options from the nak_buffer to the caller's buffer.
         */
            *lenp = (int)(nakp - nak_buffer);
            BCOPY(nak_buffer, inp, *lenp);
            break;
        case CONFREJ:
            *lenp = (int)(rejp - inp);
            break;
    }

#if TRACELCP > 0
    if (traceNdx > 0) {
        LCPDEBUG((LOG_INFO, "lcp_reqci: %s\n", traceBuf));
    }
#endif
    LCPDEBUG((LOG_INFO, "lcp_reqci: returning CONF%s.\n", CODENAME(rc)));
    return (rc);   /* Return final code */
}

/*
 * lcp_up - LCP has come UP.
 */
static void lcp_up(fsm *f)
{
    lcp_options *wo = &lcp_wantoptions[f->unit];
    lcp_options *ho = &lcp_hisoptions[f->unit];
    lcp_options *go = &lcp_gotoptions[f->unit];
    lcp_options *ao = &lcp_allowoptions[f->unit];

    if (!go->neg_magicnumber)
        go->magicnumber = 0;
    if (!ho->neg_magicnumber)
        ho->magicnumber = 0;

    /*
    * Set our MTU to the smaller of the MTU we wanted and
    * the MRU our peer wanted.  If we negotiated an MRU,
    * set our MRU to the larger of value we wanted and
    * the value we got in the negotiation.
    */
    ppp_send_config(f->unit, LWIP_MIN(ao->mru, (ho->neg_mru? ho->mru: PPP_MRU)),
                (ho->neg_asyncmap? ho->asyncmap: 0xffffffffl),
                ho->neg_pcompression, ho->neg_accompression);
    /*
    * If the asyncmap hasn't been negotiated, we really should
    * set the receive asyncmap to ffffffff, but we set it to 0
    * for backwards contemptibility.
    */
    ppp_recv_config(f->unit, (go->neg_mru? LWIP_MAX(wo->mru, go->mru): PPP_MRU),
                (go->neg_asyncmap? go->asyncmap: 0x00000000),
                go->neg_pcompression, go->neg_accompression);

    if (ho->neg_mru)
        peer_mru[f->unit] = ho->mru;

    lcp_echo_lowerup(f->unit);  /* Enable echo messages */

    link_established(f->unit);
}

/*
 * lcp_down - LCP has gone DOWN.
 *
 * Alert other protocols.
 */
static void lcp_down(fsm *f)
{
    lcp_options *go = &lcp_gotoptions[f->unit];

    lcp_echo_lowerdown(f->unit);

    link_down(f->unit);

    ppp_send_config(f->unit, PPP_MRU, 0xffffffffl, 0, 0);
    ppp_recv_config(f->unit, PPP_MRU,
                (go->neg_asyncmap? go->asyncmap: 0x00000000),
                go->neg_pcompression, go->neg_accompression);
    peer_mru[f->unit] = PPP_MRU;
}

/*
 * lcp_starting - LCP needs the lower layer up.
 */
static void lcp_starting(fsm *f)
{
    link_required(f->unit);
}

/*
 * lcp_finished - LCP has finished with the lower layer.
 */
static void lcp_finished(fsm *f)
{
    link_terminated(f->unit);
}

#if 0
/*
 * print_string - print a readable representation of a string using
 * printer.
 */
static void print_string(
    char *p,
    int len,
    void (*printer) (void *, char *,...),
    void *arg
    )
{
    int c;

    printer(arg, "\"");
    for (; len > 0;--len) {
        c = *p++;
        if (' ' <= c && c <= '~') {
            if (c == '\\' || c == '"')
                printer(arg, "\\");
            printer(arg, "%c", c);
        }
        else {
            switch (c) {
                case '\n':
                    printer(arg, "\\n");
                    break;
                case '\r':
                    printer(arg, "\\r");
                    break;
                case '\t':
                    printer(arg, "\\t");
                    break;
                default:
                    printer(arg, "\\%.3o", c);
            }
        }
    }
    printer(arg, "\"");
}

/*
 * lcp_printpkt - print the contents of an LCP packet.
 */
static char *lcp_codenames[] = {
    "ConfReq", "ConfAck", "ConfNak", "ConfRej",
    "TermReq", "TermAck", "CodeRej", "ProtRej",
    "EchoReq", "EchoRep", "DiscReq"
};

static int lcp_printpkt(
    u_char *p,
    int plen,
    void (*printer) (void *, char *,...),
    void *arg
    )
{
    int code, id, len, olen;
    u_char *pstart, *optend;
    u_short cishort;
    u32_t cilong;

    if (plen < HEADERLEN)
        return 0;
    pstart = p;
    GETCHAR(code, p);
    GETCHAR(id, p);
    GETSHORT(len, p);
    if (len < HEADERLEN || len > plen)
        return 0;

    if (code >= 1 && code <= sizeof(lcp_codenames) / sizeof(char *))
        printer(arg, " %s", lcp_codenames[code-1]);
    else
        printer(arg, " code=0x%x", code);
    printer(arg, " id=0x%x", id);
    len -= HEADERLEN;
    switch (code) {
        case CONFREQ:
        case CONFACK:
        case CONFNAK:
        case CONFREJ:
            /* print option list */
            while (len >= 2) {
                GETCHAR(code, p);
                GETCHAR(olen, p);
                p -= 2;
                if (olen < 2 || olen > len) {
                    break;
                }
                printer(arg, " <");
                len -= olen;
                optend = p + olen;
                switch (code) {
                    case CI_MRU:
                        if (olen == CILEN_SHORT) {
                            p += 2;
                            GETSHORT(cishort, p);
                            printer(arg, "mru %d", cishort);
                        }
                        break;
                    case CI_ASYNCMAP:
                        if (olen == CILEN_LONG) {
                            p += 2;
                            GETLONG(cilong, p);
                            printer(arg, "asyncmap 0x%lx", cilong);
                        }
                        break;
                    case CI_AUTHTYPE:
                        if (olen >= CILEN_SHORT) {
                            p += 2;
                            printer(arg, "auth ");
                            GETSHORT(cishort, p);
                            switch (cishort) {
                                case PPP_PAP:
                                    printer(arg, "pap");
                                    break;
                                case PPP_CHAP:
                                    printer(arg, "chap");
                                    break;
                                default:
                                    printer(arg, "0x%x", cishort);
                            }
                        }
                        break;
                    case CI_QUALITY:
                        if (olen >= CILEN_SHORT) {
                            p += 2;
                            printer(arg, "quality ");
                            GETSHORT(cishort, p);
                            switch (cishort) {
                                case PPP_LQR:
                                    printer(arg, "lqr");
                                    break;
                                default:
                                    printer(arg, "0x%x", cishort);
                            }
                        }
                        break;
                    case CI_CALLBACK:
                        if (olen >= CILEN_CHAR) {
                            p += 2;
                            printer(arg, "callback ");
                            GETSHORT(cishort, p);
                            switch (cishort) {
                                case CBCP_OPT:
                                    printer(arg, "CBCP");
                                    break;
                                default:
                                    printer(arg, "0x%x", cishort);
                            }
                        }
                        break;
                    case CI_MAGICNUMBER:
                        if (olen == CILEN_LONG) {
                            p += 2;
                            GETLONG(cilong, p);
                            printer(arg, "magic 0x%x", cilong);
                        }
                        break;
                    case CI_PCOMPRESSION:
                        if (olen == CILEN_VOID) {
                            p += 2;
                            printer(arg, "pcomp");
                        }
                        break;
                    case CI_ACCOMPRESSION:
                        if (olen == CILEN_VOID) {
                            p += 2;
                            printer(arg, "accomp");
                        }
                        break;
                }
                while (p < optend) {
                    GETCHAR(code, p);
                    printer(arg, " %.2x", code);
                }
                printer(arg, ">");
            }
            break;

        case TERMACK:
        case TERMREQ:
            if (len > 0 && *p >= ' ' && *p < 0x7f) {
                printer(arg, " ");
                print_string((char*)p, len, printer, arg);
                p += len;
                len = 0;
            }
            break;

        case ECHOREQ:
        case ECHOREP:
        case DISCREQ:
            if (len >= 4) {
                GETLONG(cilong, p);
                printer(arg, " magic=0x%x", cilong);
                p += 4;
                len -= 4;
            }
            break;
    }

    /* print the rest of the bytes in the packet */
    for (; len > 0;--len) {
        GETCHAR(code, p);
        printer(arg, " %.2x", code);
    }

    return (int)(p - pstart);
}
#endif

/*
 * Time to shut down the link because there is nothing out there.
 */

static void LcpLinkFailure(fsm *f)
{
    if (f->state == OPENED) {
        LCPDEBUG((LOG_INFO, "No response to %d echo-requests\n", lcp_echos_pending));
        LCPDEBUG((LOG_NOTICE, "Serial link appears to be disconnected.\n"));
        lcp_close(f->unit, "Peer not responding");
    }
}

/*
 * Timer expired for the LCP echo requests from this process.
 */

static void LcpEchoCheck(fsm *f)
{
    LcpSendEchoRequest (f);

    /*
     * Start the timer for the next interval.
     */
    LWIP_ASSERT("lcp_echo_timer_running == 0", lcp_echo_timer_running == 0);

    TIMEOUT (LcpEchoTimeout, f, lcp_echo_interval);
    lcp_echo_timer_running = 1;
}

/*
 * LcpEchoTimeout - Timer expired on the LCP echo
 */

static void LcpEchoTimeout(void *arg)
{
    if (lcp_echo_timer_running != 0) {
        lcp_echo_timer_running = 0;
        LcpEchoCheck ((fsm *) arg);
    }
}

/*
 * LcpEchoReply - LCP has received a reply to the echo
 */
static void lcp_received_echo_reply(fsm *f, int id, u_char *inp, int len)
{
//    u32_t magic;
    
//   (void)id;

    /* Check the magic number - don't count replies from ourselves. */
//    if (len < 4) {
//        LCPDEBUG((LOG_WARNING, "lcp: received short Echo-Reply, length %d\n", len));
//        return;
//    }

//    GETLONG(magic, inp);

//    if (lcp_gotoptions[f->unit].neg_magicnumber
//        && magic == lcp_gotoptions[f->unit].magicnumber) {
//
//        LCPDEBUG((LOG_WARNING, "appear to have received our own echo-reply!\n"));
//        return;
//    }

    /* Reset the number of outstanding echo frames */
    lcp_echos_pending = 0;
}

/*
 * LcpSendEchoRequest - Send an echo request frame to the peer
 */

static void LcpSendEchoRequest(fsm *f)
{
    u32_t lcp_magic;
    u_char pkt[4], *pktp;

    /*
    * Detect the failure of the peer at this point.
    */
    if (lcp_echo_fails != 0) {
        if (lcp_echos_pending++>= lcp_echo_fails) {
            LcpLinkFailure(f);
            lcp_echos_pending = 0;
        }
    }

    /*
    * Make and send the echo request frame.
    */
    if (f->state == OPENED) {
        lcp_magic = lcp_gotoptions[f->unit].magicnumber;
        pktp = pkt;
        PUTLONG(lcp_magic, pktp);
        fsm_sdata(f, ECHOREQ, (u_char)(lcp_echo_number++ & 0xFF), pkt, (int)(pktp - pkt));
    }
}

/*
 * lcp_echo_lowerup - Start the timer for the LCP frame
 */

static void lcp_echo_lowerup(int unit)
{
    fsm *f = &lcp_fsm[unit];

    /* Clear the parameters for generating echo frames */
    lcp_echos_pending      = 0;
    lcp_echo_number        = 0;
    lcp_echo_timer_running = 0;

    /* If a timeout interval is specified then start the timer */
    if (lcp_echo_interval != 0)
        LcpEchoCheck (f);
}

/*
 * lcp_echo_lowerdown - Stop the timer for the LCP frame
 */

static void lcp_echo_lowerdown(int unit)
{
    fsm *f = &lcp_fsm[unit];

    if (lcp_echo_timer_running != 0) {
        UNTIMEOUT (LcpEchoTimeout, f);
        lcp_echo_timer_running = 0;
    }
}

#endif /* PPP_SUPPORT */
